Metrology
Portable CMM Helps the Creation of Off-Road Dream Machines
Customized special-vehicle manufacturer simplifies prototype construction with the ROMER measuring arm
Published: Wednesday, July 7, 2010 - 06:53
Brothers Jürgen and Andreas Hellgeth are entrepreneurs with a passion. Their interests, both business and leisure, center on motor sports and off-road vehicles. Their successful business designing and building off-road vehicles began by creating special vehicles for their own use. A converted racing Unimog with a twin-turbo, midmounted engine even secured them the overall winner’s spot in the Dresden-Breslau Rally in 2008 (see figure 1). Given their off-road expertise and a growing demand for individualized details and customized vehicle bodies, the Hellgeths have built up a business that has gained a good name among its customers.
The snowy forests and mountains surrounding their Wurzbach-Rodacherbrunn facility in southern Thüringen proved the perfect place for building all-terrain vehicles—the dozens of test tracks right on the doorstep are frequently used for product testing (see figure 2). Today, the family’s business activities focus on customized special solutions for wheeled vehicles and the modernization, conversion, and sale of tracked vehicles.
Hellgeth’s strength lies in the single-minded pursuit of fulfilling customers’ wishes in every area of vehicle-making. “Only a few vehicle body manufacturers also concern themselves with automotive engineering,” says Andreas Hellgeth. “We design and optimize all components to meet the exact wishes of the customer, whether it is a gearbox, the best wheel and tire combination, brakes, chassis, suspension, shock absorbers, winches, or tanks.”
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Figure 1: The successful Unimog. With help from the ROMER measuring arm, Jürgen and Andreas Hellgeth converted the vehicle and went on to win the Dresden-Breslau Rally in 2008.
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Figure 2: Work and leisure vehicles—a Hägglund in its element
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Depending on the company’s production capacity and order book, each year Hellgeth sells 30–50 tracked vehicles, which come originally from Swedish manufacturer Hägglund and are converted at the Rodacherbrunn facility. These vehicles are suitable for transport and operating over difficult terrain. Equipped with a modern diesel engine and capable of carrying up to 16 people, Hägglunds are in service all over the world—including in the Arctic and high-alpine regions.
The challenge: easy data import into CAD and elimination of errors
The construction and conversion of all the vehicles are carried out by hand. The individuality of each model demands a great deal of flexibility—from the designers and mechanics, and from the technical equipment. Extraordinary customer wishes can only be realized if the equipment is innovative and efficient. In the end, many of the components for the conversions must first be made as prototypes.
Hellgeth demands a lot from its metrology equipment. “The vehicle cabs have hardly a 90-degree angle anywhere,” says Martin van der Koelen, Hellgeth CAD specialist, describing the difficulties. “You reach your wits’ end very quickly using a measuring rule and tri-square.”
For the Hellgeth designers, the focus is on two issues: measurement results that are simple to transfer into CAD, and the need to eliminate one potential source of error—the measurement of patterns. “The establishment of fixed measuring points directly on the component is quicker and much more reliable,” says van der Koelen.
The interest in flexible coordinate metrology quickly developed into a search for the right system. Different measuring arm manufacturers presented their approaches to solving the problem, but only the Hexagon Metrology applications engineers came up with the solution that stood out from the rest. The ROMER measuring arm was demonstrated to the vehicle builders and perfectly fulfilled the need for absolute flexibility and the exacting quality requirements at Hellgeth.
Systematic approach, quick measurement
Following a short induction training session on the hardware and software, van der Koelen developed his first measuring processes and got his co-workers involved in the new technology. The measuring arm is used at Hellgeth during the development phase of individualized components to speed up and simplify working with different prototypes.
“Naturally, we have a definite idea of how the new component should look from the beginning,” explains van der Koelen. “The ROMER arm helps us determine the dimensional limits we have to work toward within the installation space.”
Helgeth vehicle builders always adopt a strictly systematic approach to their tasks. Three questions precede the actual measuring of the installation space:
• What precisely is the purpose of the measurement, and which geometries are to be captured?
• What is the exact sequence of the individual measured points?
• Would initial sketches be helpful?
“A short time ago, we modified the engine air-intake duct on a tracked vehicle and then had to replace the seat console,” says van der Koelen. “We needed to determine the correct bolting points, the dimensions of the floor and side walls, and the space required for the air filter. We then wished to import the data without too much manipulation into our CAD system. Based on the measurements obtained, we were then able to produce the initial designs. The measuring itself was done fairly quickly because we had planned how we were going to do it well in advance.”
Light, flexible, and portable measuring arm
Another application of the ROMER arm is the measurement of existing components. “For one job we had to copy an existing part,” says van der Koelen. “Measuring with the arm made it easy to import the data into CAD.”
The ROMER measuring arm has completely met the designer’s expectations. The arm is now an integral part of many of the company’s key projects. The ROMER measuring machine also contributed to the success in motor sports by supplying base data for the parts specially designed for the racing Unimog.
From the start, the advice, training, and service received from Hexagon Metrology have been exemplary. “The Hexagon Metrology engineer assigned to us certainly put in a convincing performance,” recalls Andreas Hellgeth. “We felt we were very well advised. On top of that, the ROMER arm simply had certain characteristics that could not be matched by the alternatives—it’s very low weight, for example. We even use the arm inside the driver’s cab.” (See figre 3.)
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Figure 3: From empty cabin to finished converted transport vehicle. ROMER measuring-arm flexibility makes it possible to measure the installation space inside the chassis.
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“We can even measure on the milling machine,” adds Jürgen Hellgeth. “The flexibility of the ROMER measuring arm is exactly what we need. I think every manufacturer of prototypes would have use for it.”
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